Improvement in instruments for measuring distances



J. 1. DALY- instrument for Measuring Distances,

No. 53,420. Patented March 27, 1866.

f" \h R N .v n mg, a N

&\ Ni I H UNITED STATES PATENT OEETCE.

JOHN J. DALY,-OF NEW ORLEANS, LOUISIANA.

Specification forming part of Letters Patent No. 53,420, dated March 27, 1866.

To all whom it may concern.-

Be it known that I, JOHN J. DALY, of New Orleans, in the parish of Orleans and State of Louisiana, have invented a new and Improved Instrument for lIIeasuring Distances; and I do hereby declare that the' following is a full and exact description, to wit The nature of my invention consists in the arranging; a scale so as to represent the chord of an arc and adjustingit to a rod corresponding to the radius of said are. On either side of the aperture of the scale are lines, on which are placed figures that indicate the number of yards distant an object would bewhen viewed at such an an gle: By means of a ratch and a cog-wheel the index is moved so as to take in the full size or dimension of the object viewed.

Ready-reckoning measurer of distance is the name 1 give my instrument, of which, as shown in the drawings, Figure 1 represents a perspective View; Fig. 2, a longitudinal elevation, and Fig. 3 a transverse section, of which A is the scale; B, index; 0, aperture; D, thumb-screw; E, clamp-screw; F, rod, and G eye-piece.

On the scale, half an inch represents one degree and twenty-eight inches,and sixty-five hundredths (28- represents the corresponding' radius on the rod. By shortening the radius in proportion to the increased size of the object viewed, the same scale serves for many difi'erent sized objects.

Dimensions of the lines on the scale (from base of aperture Degrees. For 30 yards .3.82

' Degrees.

For yards ..1.63714 Dimensions of the points on the rod (from eye-piece:)

Inches. Minus.

Ft. In. For an object of 4 10 it is. 35.565517 5 0 .3438 5 2 .33.2709677 5 3 .32.742857 5 4 32.23125 5 .5 .3L7353846 5 6 31.254545 5 8 .30.33528 H (4 5 9 4 L4 Ft. In. Inches. Minus. For an ob ect of 5 11; 1s. 29.46857 O 28.65 (i 3 27.504 6 6 264461538 7 l) 24.55715 u a 7 6 "2292 a S l 21.4875 8. O 20.22353 44 u 9 0 u 1g 1' u 10 0 ....17.19 11 0 .15.b272725 a u 12 0 u 143 5 a 13 0 .13.2230769 14 0 12.278575 15 0 .11.;46 16 O 10.74375 17 0 .10.11176 a. 44 18 0 u 955 u 19 O 9.0473684 20 O 8.595 0 6.876 3O 0 5.73 O 4.91143 u u 0 0 cc 2975, a 0 3.82

u p u 5 0 n 34:38 44 O 3.12545 u r. 0 4c 25 5 u I allow three-tenths of an inch for the space between the eye-piece of the instrument and the crystalline lens of the spectators eye.

The instrument can be used in a horizontal or in any other direction, as the objector dimension viewed may suggest, and can also be used with or without a telescope or perspectiveglass. If a perspective-glass be used, the eyepiece of the glass should be the fixed point and fixed at the eye-piece of the distance,

measurer.

Conditions to be complied with when using the ready-reckonin g measurer of distance: An object viewed through this instrument is diminished in apparent size in proportion to its distance from the eye. Therefore, the size of object being known and the scale placed at a point on the rod marked for such-sized object, and the index being moved so as to take in fully and exactly, in the open space of the aperture, the dimension of the object viewed, the figures on the line at the base of the index will indicate the distance in yards. The eyepiece should be held close as possible to the eye.

To increasethe capacity of the instrument it is only necessary to view a large object with the scale placed at a point on the rod marked forasmaller size, thus: If the dimension viewed be one hundred feet and the scale be placed at a point on the rod marked for an object of ten feet, the actual distance will be ten times as great as that indicated on thescale, and so on of other sizes and proportions.

The size of objects can be found on the rod when the distance is known. The index being fixed at the line indicating such distance and the scale moved on the rod till the object viewed fill the aperture, at the point on the rod where the scale rests will be found the size of the object.

bination with the rod F and eye-piece (w JOHN J. DALY.

\Vitnesses J. Bonn, L. ZELLER. 

